The practice of mentorship is a critical focus in science, technology, engineering, mathematics, and medicine (STEMM) disciplines. This quasi-experimental study investigated the efficacy of undergraduate mentor training in biomedical sciences programs in the NIH-funded Building Infrastructure Leading to Diversity (BUILD) initiative comprised of research-rising institutions. We used data from the Higher Education Research Institute's Faculty Survey (2016-17 and 2019-20). In cross-sectional comparisons of 379 BUILD-trained faculty with 755 colleagues who were not BUILD-trained, those who participated in BUILD mentor training reported more engagement with mentees. Utilizing propensity score matching of 314 with longitudinal cases, mentoring confidence and engagement were stronger over time for BUILD-trained faculty. Findings suggest BUILD mentor training yields positive results for undergraduate mentors at research-rising institutions.